MOSSBAUER SPECTROMETRY STUDY OF MAGNESIOFERRITE PARTICLES

Fine particles of ferrimagnetic MgFe2O4 were synthesized through a sol-gel supercritical drying procedure, then cold-pressed and heated at 500 and 800-degrees-C. These materials were characterized by Mossbauer spectrometry in the temperature range 25-298 K, and in the presence of a small applied magnetic field. The Mossbauer measurements show that heat treatment results in the formation of a small percentage of alpha-Fe2O3, an increase in the mean particle size and hyperfine magnetic field, and a decrease in the inversion parameter of the magnesioferrite. An average anisotropy constant equivalent to the bulk magnetocrystalline anisotropy is estimated for particles with diameter D = 14 nm.